1. Field of the Invention
The present invention pertains to a method and apparatus for forming a sheet of paper, wet-type nonwoven fabric or the like, and more particularly to a novel sheet forming method and apparatus which permits easy modification of the endlesswire arrangements on the basis of sheet-making conditions, including the kinds of raw fibrous materials, freeness or consistency thereof, filler conditions, basis weights, and machine speeds, to achieve excellent fiber orientation, yield and physical properties of the sheet for any kind of sheet products.
2. Related Art
The conventional sheet forming techniques in the manufacture of mass-production paper have been specialized corresponding to kinds of paper; i.e., newsprint paper (produced of a pulp mixture of TMP, BCTMP, SGW, RGP, CGP, GP, NBKP, newsprint waste paper and the like); kraft paper (produced essentially of NUKP); wood-free printing paper and coating base paper (produced essentially of LBKP); liner board (produced essentially of high-yield NUKP and waste corrugated board); corrugating medium (produced essentially of SCP and waste corrugated board); and domestic tissue paper (produced essentially of LBKP and newsprint or magazine waste paper).
Furthermore, long-fiber material such as paper mulberry, Mitsumata (Edgeworthia papyrifera), hemp or rayon is used to manufacture Japanese traditional paper. Powder of calcium carbonate, aluminum hydroxide or the like is the essential material for the production of nonflaming paper, whereas synthetic fibers such as aramid fiber (Du Pont's trade name), polyester fiber or nylon fiber, chemical fibers such as rayon fiber, inorganic fibers such as fibers of glass, slag or cement, and fibers of metal such as stainless steel are used to manufacture speciality papers and nonwoven fabrics for various uses. For the production of these kinds of speciality papers and nonwoven fabrics, various special types of paper machines such as a short-wire former, a cylinder mold or an inclined-wire former have been utilized.
Modifications to or improvements on the aforesaid specialized paper-making machines have been naturally required due to the change with the times, to technology development and innovation, to variations in market economy, and to changes in raw materials, basis weights or physical properties of the products.
In some cases for specific paper products, the operations of paper-making machines have been forced to be suspended for a long period due to inventory adjustment. However, even though reconstruction of the paper-making machine, the operation of which has been suspended for a long time, is planned to be able to manufacture different paper products, a vast expense is required due to space problems, sectional drive assemblies and transformer station requirements, and because additional pile driving work is required for the machine foundation in the building, which is usually two-storied.
Conventional paper-making machines for the manufacture of mass-production papers include a gap former for newsprint paper; a multi short-wire former or a multi on-top former for liner board; a hybrid former for wood-free printing paper; and a gap or suction former for tissue paper. However, each of these paper machines is specialized and cannot be operated under conditions other than those for which it was specifically designed; therefore their operations are limited due to the kinds of raw fibrous material used, consistency or freeness of the stock, basis weights, paper-making speeds, and product grades, resulting in a loss of flexibility in an industry which intrinsically requires vast investment.
Furthermore, conventional paper-making machines designed for the production of speciality papers include an inclined-wire former with a pond slice, a suction former, a multi-vat former, a short-wire former, and a shake-type Fourdrinier machine. Each of these paper machines is also specialized and cannot be operated under conditions other than those for which it was specifically designed; therefore their operations are limited due to the kinds of raw fibrous material, consistency or freeness of the stock, basis weights, paper-making speeds, and product grades, resulting in a loss of flexibility in the pulp and paper industry.
Additionally, the pulp and paper industry runs the gamut of gigantic firms with annual sales of one trillion yen to small mills with one hundred million yen in annual sales. Specialization of the paper-making machines, while contributing to the sales of machine suppliers, results in most of the firms in the pulp and paper industry making vast investments which do not even reach an annual turnover ratio of sales of 1/2. Thus, management is subjected to price pressure, resulting in loss of flexibility.